When working with vectors $\,\langle a,b\rangle\,$,
two unit vectors
are singled out as being particularly important, and are given special names:
$$
\begin{gather}
\hat{\smash{\imath}\vphantom{i}} = \langle 1,0\rangle\cr
\hat{\smash{\jmath}\vphantom{j}} = \langle 0,1\rangle
\end{gather}
$$